Solid-state storage devices can shift over time. For example, memory cell leakage (often referred to as charge leakage), memory cell damage and other disturbances to memory cells can alter the read voltage levels of the memory cells. Thus, the read reference voltages can shift over time. If the read voltage level of a memory cell shifts past a read reference voltage, a data error occurs, as the value of the data read from the memory cell is different than the value of the data that was written to the memory cell. Adaptive reference voltage tracking algorithms track variations in the solid-state storage channel and, consequently, help maintain a set of updated channel parameters. The updated channel parameters are used, for example, to adjust the read reference voltages.
After a non-volatile memory page is programmed, charge leakage can be observed through the tunnel oxide impacting the voltage distribution and the read reference voltages. This phenomenon is often referred to as quick-charge loss, short term data retention or low temperature data retention (LTDR). The charge leakage can negatively impact post-programming activities including the adaptive reference voltage tracking algorithm. The charge leakage usually settles within a matter of minutes but depends on, for example, the media type, the media generation and the usage condition (such as temperature and number of program-erase cycles).
A need exists for improved techniques for adapting read reference voltages that mitigate for such charge leakage effects.